Solid oxide fuel cell (SOFC) technology has the potential to generate electrical power at high efficiency. For example, SOFCs can generate electrical power at higher efficiency than is achieved by using power from a main engine shaft from an aircraft to run a generator. Hence, unlike the existing auxiliary power unit (APU) which is turned off once the main engines are started, a solid oxide fuel cell power unit (SOFCPU) would operate throughout the flight to maximize fuel savings. SOFCPU's are expected to be somewhat heavier than turbine APUs resulting in a heavier aircraft. A key hurdle to demonstrate the feasibility of a SOFCPU is to show that the increase in fuel consumption due to the increase in aircraft weight is less than the savings obtained by operation of the SOFCPU.